Recovery of globulin from cottonseed



Patented Mar. 26, 1940 a p I I I r hurra stares PATENT QPFFECE anonymity or eLonumN mom corrousann Harold S. Glcott, hittsburgh, Pa., assignor to ilottonResearch Foundation, a corporation Tennessee No Drawing. Application January 13, 1939,

Serial No. 250,749

' '2 eieime. (omen-112 This invention relates to the recovery of proteed by the demand for cotton lint. Cottonseed tein from cottonseed and consists in procedures meats are extremely rich in protein. My invenwhereby protein may be recovered from this tion concerns the recovery of industrially valusourdcie in maximum quantity and in optimum able protein from this rich and abundant source.

con tion.

In an application for Letters Patent of the The crushing f Cottonseed meats United States, filed September 21, 1938, by Ralph F. Nickerson, Serial No. 230,993, a method of The Common Practice m the Preparatlon procedure for the recovery of rotein from c 13,, Cottonseed meats for the hydraulic preSSing 0 tonseed is described and c1aimed That method consists of passing them between several pairs of m involves the extraction of protein from properly 3105913 Set T9115 e then givmg them? hlgh' prepared cottonseed meal by means of a dilute temperature cookmg treatment- Tms m' alkali solution. The protein that is thus re- Pereture Processing destroys many of the covered may be l ifi d as a globulin G1b able characteristics of the protein and causes a ulins are insoluble in water, but they are soluble deal of color fixation- There further 9 15 in dilute alkali or acid solutions, and in solutions 1961510" in that the s q ent pressing operation of salts. I have discovered a procedure whereby leaves in the meal sllbstmltml es1due of the extraction of the protein from the meal may per cent) and $1115 re1due PY as to be fi t d by means of a salt solution; and I interfere with protein extraction by inhibiting the have found that in following my procedure I penetretlqn of aqueous solvents: 20 need not take certain precautions that must be A practlcable dfi efiectmg relatlvely taken in the alkali procedure alluded to in order complete separation of oil from cottonseed meats, to avoid discoloration. Discoloration due to pig- Y F danger from heat effects by extra?" ments found in cottonseed is enhanced by the 3 Solvents- By thls Preatment alkaline treatment; and consequently it is the cottonseed 01] content may readily be rerequisite to the successful practice of the alkaline duced to a negligible one p cent, o less, and treatment that the greater part of the hull pardegradation produQed by temperature may tides be removed preliminarily fr m the meal, be avoided. Several orgamc solvents are combefore it is subjected to the action of the'alkali pleiely adequate dissmve the (and the solution, and that in the course of procedure an gossypol as Well, h chief pigment present) of antioxidant be used. I have found that my proound cottonseed meal' cedure, involving the use of a solution of neutral Cracked kernels as obtmned m an Salt instead of a solution of alkali, may be can mill are superior to rolled kernels in afiording, fled out upon meal from which the nun pap after extraction a white, fat-free meal. The ticles have not been removed, and may be carried grind-mg may easfly be effected wlth Seeds 10w out without the use of an antioxidant, and yet a moisture content percent) Low m E that is almost is believed to be conducive to most rapid action product may be obtai white in c l r. Furthermore, in rccedure is by s01vent5- I have found that finely dlvlded o o y p meal yields its oil and gossypol most readily, and,

inexpensive.

In the past few years the proteins as a. spec after the solvent extraction, is better suited to the aterial than coarse meal.

class of chemical compound have received conisolation P 111 siderable industrial development and, as a result, The speed and efiiciency with WhlCh a solvent promise to be important commercial raw mateacts are conditmned largely by t Penetratmg rials of the fut r Th more commonly used power of the solvent and the s ze of the meal proteins (casein, alb i and gelatin) are particles. Generally, the smallest meal particles rived from animal sources; but, for the enjoya best suitedto extraction- Eighty-mesh 15 3.11 ment of these. industry must compete im excellent degree of fineness, from the standpoint ably. with a. demand for them a fo0dtufis of protein extraction, to which this pulverization Proteins of vegetable origin are, consequently, of may b carri d, ut in pr t an avera e of great interest;,-,they offer the industrial consixty-mesh is afeasible and satisfactory limit. I

Asumer an almost unlimited supply and the probhave found it most satisfactory to grind the ability of a more stable price. whole meats to twenty-mesh size to extract the Among the vegetable sources of protein, cotoil with solvents, and after removal of the residf 'tonseed occupies aunique position. There is an ual solvent,. to regrind the dried meal to the i E'enormous annual production which is guaranrequisite fineness.

Solvent extraction of raw cottonseed meal Leaching of cottonseed flour When the cottonseed meats have been ground to a fine meal and rendered oiland gossypolfree, they contain about 60 percent of protein on a dry basis. The residual 40 percent consists of sugars, gums, non-protein nitrogenous substances, interstitial cellulosic materials including pentosans, and probably other (as yet unidentified) substances. A fraction of the cottonseed protein is soluble in water; but by far the larger portion is insoluble in water. It is the latter fraction of the protein content of cottonseed meats whose extraction and recovery are the object of my invention.

If without further preparation the proteins be extracted from the meal and then precipitated, the precipitate forms a sticky, voluminous agglomerate that tends to adsorb and occlude the water-soluble proteins, and other extraneous substances. Such undesirable effect may to a large extent be minimized by leaching the cottonseed meal with water, and so removing the watersoluble materials, before proceeding to extract the proteins that are insoluble in water. The details of the procedure that I have taken with success are these: Beginning with fatfree cottonseed meal, 15 parts are thoroughly wet with 150 parts of water (preferably warm-35-50 C.) and extracted for one to two hours, with occasional stirring. The wash-water is then removed, as by centrifugation, and discarded or retained for the isolation of by-products. Possible contaminants of the protein product are thus removed.

Digestion and extraction The wet meal (residue of 15 parts original oilfree meal) is then dispersed in 70-80 parts of warm 3-percent salt (sodium chloride) solution. After standing for one to two hours, with occasional stirring, a first extract is removed by centrifugation. The residual meal is re-dispersed in a second body of 70-80 parts of warm 3-percent salt solution. After standing again for one to two hours the mixture is again centrifuged. The two extracts are now combined. If any fine meat remains in suspension it is removed, preferably by centrxiugation.

The use of sodium chloride is recommended, because of its availability at low cost. However, sodium sulfate, sodium sulfite, disodium phosphate, and other salts of similar character are also effective as extracting agents, and may be used at the same degree of concentration. In this connection I usethe term salt to include, not sodium chloride alone, but the other related salts also that have been named and alluded to above.

Precipitation of the protein The clear extract in the salt solution is precipitated by adjusting the pH to 3.9-4.2, by the addition, with vigorous stirring, of acid-typica1ly of 10-percent sulfuric acid. The protein separates as flocks and settles to the bottom of the vessel. The supernatant liquor is removed by any suitable means, and the protein slurry is then centrifuged to remove the residual water and salt.

The cake then is washed with water and is dried on trays in a drying tunnel. The yield is approximately 3 parts of dried cottonseed globulin. This amounts to 20 percent by weight of the original meal.

At no point in the procedure is the temperature raised higher than 50 C.

Physical properties of cottonseed proteins The iso-electric point of a protein may be defined as the region of minimum properties. In aqueous solutions proteins act both as acids and as bases: they combine with alkali to form soluble salts, and they combine with strong acids to form soluble complexes. There is an intermediate point in the acid-base relationship at which proteins exhibit no tendency to combine and consequently precipitate. Thus, the iso-electric point corresponds to minimum solubility. For most proteins this neutral point or minimum point lies within the range of slight acidity, in the pH range 4 to 5. In fact, the iso-electric point of the water-soluble protein of cottonseed is approximately at pH 4.5. On the other hand, the principal protein fraction of cottonseed, the globulin, has a higher iso-electric point, which appears to lie between pH values 6.3 and 6.8. For all practical purposes this value corresponds to that of distilled water; and the significance is that, unlike most proteins, cottonseed globulin exhibits its minimum behavior in pure water. The importance of this difference from other proteins is immediately apparent in the fact that the globulin shows no tendency toswell or dissolve in water. This property indicates peculiar suitability of the protein under consideration for particular uses, such as in the production of waterproof glues and in the preparation of water-resistant textile and paper sizes and finishes. In the field of synthetic protein products, such as plastics, this property is of yet greater potential significance.

In carrying out the process as described above it will be observed that the water-soluble proteins present in the starting material (cottonseed meal) are in the main extracted and rejected. The protein material that is recovered is a salt-extracted protein or protein association that is of minimum solubility in distilled water. On this account the product is of high industrial value.

Summary The liquoris removed by centrifugation and saved. The operation is repeated on the residue; and again the liquor is removed and added to that first removed.

To this liquor 10-percent sulfuric acid is added precipitating the globulin,

meal, separating the drying the precipitate.

rating,- washin and drying with rigorous stirring, until a pH of 3.9-4.2 is attained. 1 The precipitate is separated, washed with water, and dried. v v

I claim asmy invention:

"1. The method herein described of recovering globulin from cottonseed meal which consists in extracting with air-aqueous solution of salt a quantity of oil-free, water-leached cottonseed solution from the residue, acidifying the solution and thereby precipitating the globulin, and finally separating, and

2. The method herein described of recovering globulin from cottonseed meal which consists in extracting with a solution of sodium chloride a v quantity of oil-free, water-leached cottonseed meal, separating the solution from the residue, acidifying the solution and thereby precipitatin the globulin, and finally separating, washing, and drying thepricipitate.

3. The method herein described of recoverin globulin from cottonseed meal which consists in. extracting with an aqueous quantity of oil-free, water-leached cottonseed meal, separating the solution from the residue, acidifying to a pH value of 3.9-4.2 and thereby and finally separating, washing, and drying the precipitate.

4. The method herein described of recove globulin from cottonseed meal which consists in extracting with a 3-percent aqueous solution of salt a quantity of oil-free, water-leached cottonseed meaLseparating the solution from the residue, acidifying to a pH value of3.9-4.2 and thereby precipitating the globulin, and finally sepathe precipitate.

5. The method herein described of recovering ing, and drying globulin from cottonseed meal solution of salt a residue, dispersing the cent aqueous solution of sodium chloride with globulin from cottonseed meal which consists in extracting with a 3-percent aqueous solution of sodium chloride a quantity of oil-free, waterleached cottonseed meal, separating the solution from the residue, adding iii-percent sulfuric acid until a pH value of 3.9-4.2 is attained and thereby precipitating the globulin,fand finally separating, washing, and drying the precipitate.

6. The method herein described of recoverin globulin from cottonseed meal which consists in dispersing in an aqueous solution of salt a quantity of oil-free, water-leached cottonseed meal, with consequent solution of globulin, separating the solution from the residue, dispersing the residue in a second aqueous solution of salt, with further solution of globulin, separating the second solution from a second residue, acidifying the two so-separated solutions and thereby precipie tating the globulin, and finally separating, washthe precipitate.

'7. The method herein described of recoverin which consists in dispersing in a 3-percent aqueous solution of sodium chloride a quantity leached cottonseed meal with consequent solution of globulm, separating the solution from the residue in a second 3-perfurther solution ofglobulin, separating the second solution from a second residue;

of oil-free, watercombining 30 the two so-separated solutions and acidifying the combined solutions'to a pH value of 3.9-4.2 and thereby precipitating globulin, and finally'separating, washing, and drying the precipitate.

HAROLD S. OLCQTI 

